Kirsty Harkness with the hemp crop. Supplied

Kirsty Harkness is a grape-grower researching industrial hemp as a vineyard cover crop.

Kirsty is one year into a four-year trial using hemp as a cover crop in her Marlborough vineyards. Hemp seems to attract insect life, can suppress weed growth, and helps retain soil moisture. It can also provide an additional income stream. In the long-term, she hopes to understand the impact, if any, on vine health, productivity and ultimately wine quality.

Bob Campbell MW: Was it difficult to obtain a license to trial hemp production? What hurdles did you face?

Kirsty Harkness: Yes, initially. I said all the wrong things on my first application including the word ‘medical’ and had to start again. We also found that because it was new to the Ministry of Health (MOH), and they had a ton of applications, it was long delays. We had to do police checks, security camera’s, be over 5km from a school, not visible from a road, just to name a few. The community and the local police were very helpful through the process, and we would not have got this license last year without the help from members of the New Zealand Hemp Industries Association (NZHIA) either. So I am very thankful to be a year ahead because of everyone’s kind assistance.

BC: How do you plan to derive income from hemp production?

KH: At this stage, we have a license to sell the hemp seed as a food product. It is an exciting seed as it has Omega 3,6 & 9 (better than fish oil) and it’s high in protein. Similar to the protein amounts in beef & sheep. Here is more information on the seed.

Due to my allergies to chemicals, I am also in the process of launching two body product ranges that are all-natural, using the hemp seed oil as moisturisers and skincare.

The plant material (other than green leaf) can be sold for fibre, however, we want to use this component in the vineyard as it’s a great mulch. It holds 4-times its body-weight in water, it insulates the ground, and because of the high resins, we found weeds did not grow through it under the vines. We also believe that there are great nutritional benefits in the leaf for food, but this is a future product plan for when legislation changes. The root can also be used as a poultice for gout and arthritis, however again, it’s not a product that is allowed yet. In the meantime, the root is a tap root, therefore great at breaking up compaction in the soil, bringing up nutrients, and being an organic matter pathway once the plant is cut.

BC: Studies by the Australian Wine Research Institute clearly show that grapes can pick up eucalypt characters from the essential oils generated by gum trees. Given the strong oils produced by hemp, is it possible that the grapes and wine will become tainted?

KH: This was one of our first concerns, hence the small area plantings of 4-hectares last year over four vineyard areas. We have involved all the wine companies we supply in these discussions from the beginningand they have been very supportive. One of these wine companies produce 25,000 litres of wine from the best growing hemp area and were so excited about the results, that they plan to increase that to 100,000 litres in the coming vintage. There are some other trials going on in this wine space too, which I am eager to share but the winemakers would prefer to prove two years in a row first so watch this space.

BC: You have experienced one vintage with hemp as a cover crop. Were there any differences between the resulting wine and that of wine made without a hemp cover crop?

KH: This is a question for the winemaker… and they don’t want to talk just yet… but it’s definitely not negative. Please note we have only grown this in sauvignon blanc so far, and not red varietals.

From a growers’ point of view, I want to ensure it does not take nutrients from our vines & grapes first and foremost. You can tell I am a wee bit excited about the possibilities, so I have brought in an independent. The trial areas are being assessed by Dr Mark Krasnow over the next three years. The results he finds will be published, so everyone can find out if it’s positive or negative for us to continue.

The bees and bumblebees are so heavy-laden in pollens they sound like tractor engines, and there are more beneficial insects in the hemp area than anywhere else in the vineyard.

BC: I understand that it is impossible to get high from hemp, but the very fact that a wine has been made from grapes that used hemp as a ground cover has a certain novelty. Are you able to legally promote the wine and hemp association?

KH: It is not legal to put the picture of a hemp leaf on a food or drink product, and obviously it is not right to infuse anything into the wine. However from a novelty point of view, absolutely! Everyone keeps asking me where they can buy the wine. We are growers, so we would rather support our buyers in this space, but who knows what the future holds.